Initial JGit contribution to eclipse.org

Per CQ 3448 this is the initial contribution of the JGit project
to eclipse.org.  It is derived from the historical JGit repository
at commit 3a2dd9921c8a08740a9e02c421469e5b1a9e47cb.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 141 insertions, 0 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeStrategy.java b/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeStrategy.java
new file mode 100644
index 0000000000..e7d84c68ac
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeStrategy.java
@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2008-2009, Google Inc.
+ * Copyright (C) 2009, Matthias Sohn <matthias.sohn@sap.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.eclipse.jgit.merge;
+
+import java.util.HashMap;
+
+import org.eclipse.jgit.lib.Repository;
+
+/**
+ * A method of combining two or more trees together to form an output tree.
+ * <p>
+ * Different strategies may employ different techniques for deciding which paths
+ * (and ObjectIds) to carry from the input trees into the final output tree.
+ */
+public abstract class MergeStrategy {
+	/** Simple strategy that sets the output tree to the first input tree. */
+	public static final MergeStrategy OURS = new StrategyOneSided("ours", 0);
+
+	/** Simple strategy that sets the output tree to the second input tree. */
+	public static final MergeStrategy THEIRS = new StrategyOneSided("theirs", 1);
+
+	/** Simple strategy to merge paths, without simultaneous edits. */
+	public static final ThreeWayMergeStrategy SIMPLE_TWO_WAY_IN_CORE = new StrategySimpleTwoWayInCore();
+
+	private static final HashMap<String, MergeStrategy> STRATEGIES = new HashMap<String, MergeStrategy>();
+
+	static {
+		register(OURS);
+		register(THEIRS);
+		register(SIMPLE_TWO_WAY_IN_CORE);
+	}
+
+	/**
+	 * Register a merge strategy so it can later be obtained by name.
+	 *
+	 * @param imp
+	 *            the strategy to register.
+	 * @throws IllegalArgumentException
+	 *             a strategy by the same name has already been registered.
+	 */
+	public static void register(final MergeStrategy imp) {
+		register(imp.getName(), imp);
+	}
+
+	/**
+	 * Register a merge strategy so it can later be obtained by name.
+	 *
+	 * @param name
+	 *            name the strategy can be looked up under.
+	 * @param imp
+	 *            the strategy to register.
+	 * @throws IllegalArgumentException
+	 *             a strategy by the same name has already been registered.
+	 */
+	public static synchronized void register(final String name,
+			final MergeStrategy imp) {
+		if (STRATEGIES.containsKey(name))
+			throw new IllegalArgumentException("Merge strategy \"" + name
+					+ "\" already exists as a default strategy");
+		STRATEGIES.put(name, imp);
+	}
+
+	/**
+	 * Locate a strategy by name.
+	 *
+	 * @param name
+	 *            name of the strategy to locate.
+	 * @return the strategy instance; null if no strategy matches the name.
+	 */
+	public static synchronized MergeStrategy get(final String name) {
+		return STRATEGIES.get(name);
+	}
+
+	/**
+	 * Get all registered strategies.
+	 *
+	 * @return the registered strategy instances. No inherit order is returned;
+	 *         the caller may modify (and/or sort) the returned array if
+	 *         necessary to obtain a reasonable ordering.
+	 */
+	public static synchronized MergeStrategy[] get() {
+		final MergeStrategy[] r = new MergeStrategy[STRATEGIES.size()];
+		STRATEGIES.values().toArray(r);
+		return r;
+	}
+
+	/** @return default name of this strategy implementation. */
+	public abstract String getName();
+
+	/**
+	 * Create a new merge instance.
+	 *
+	 * @param db
+	 *            repository database the merger will read from, and eventually
+	 *            write results back to.
+	 * @return the new merge instance which implements this strategy.
+	 */
+	public abstract Merger newMerger(Repository db);
+}